foo.cc: In function ‘bool cmp(t, t)’:
foo.cc:13:25: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
   13 | return a.x<b.x||a.x==b.x&&a.y<b.y;
      |                 ~~~~~~~~^~~~~~~~~
foo.cc: In function ‘int main()’:
foo.cc:53:9: warning: unused variable ‘u’ [-Wunused-variable]
   53 | int k,l,u;k=read();l=read();
      |         ^